Reports from Gaza's Hamas-controlled Health Ministry said Tuesday that two Palestinians were killed in what was described as an assassination by an Israeli military drone.
Eyewitnesses and paramedics said an Israeli missile hit a motorbike, killing two riders, which Israeli army spokesman has denied.
Eyewitnesses identified the men as members of the Islamic Jihad militant group, reports Reuters.
However apex leaders in Hamas has also declared a new "intifada" in the wake of US President Donald Trump's decision to recognize Jerusalem as Israel's capital.
The latest one, code-named Operation Protective Edge, took place in the summer of 2014 and resulted in the deaths of more than 2,200 Palestinians.
Rocket alarm sirens blared across communities surrounding the Gaza Strip, but the rocket fire appeared to be aimed at the coastal city of Ashkelon, some 20 kilometers away.
A rocket that was sacked from Gaza at around 11:30 PM on Monday night was intercepted by an Iron Dome battery over the city of Ashkelon.
The circumstances of the incident, which occurred near Gaza's northern border with Israel, were initially unclear. The rocket was intercepted by an Iron Dome anti-missile battery.
A network of Gaza tunnels allowed Hamas gunmen to blindside Israel's superior forces during the 2014 war and the Israelis, with United States help, have since stepped up work on counter-measures.
Shortly after midnight on Tuesday, Israeli forces attacked Hamas targets in the northern Gaza Strip after Palestinians fired a rocket toward the southern city of Ashkelon, the army said. "The IDF holds Hamas responsible for these aggressive acts originating from the Gaza Strip". The group vowed revenge on Sunday.
Four other Gazans, including two Hamas militants, have died since the announcement last Wednesday.